1. Field of the Invention
This invention pertains to an intumescent composition comprising a polymer and a non-flaming, phosphorus-containing intumescent preservative agent.
2. Description of the Prior Art
It is known that a substrate may be protected from heat and fire by the application of an intumescent composition. Intumescent compositions of the prior art usually contain an intumescent agent having at least three components, i.e., a carbonific, a spumific, and a catalyst; and they are typically characterized by the disadvantages of high cost, low spreading rate, relatively poor efficiency, poor water resistance, and poor weatherability.
As disclosed in U.S. Pat. No. 3,535,130, it has been discovered that a one-component intumescent agent has advantages over multicomponent intumescent agents. However, the intumescent agents of said patent are reported to have poor adherence to substrates and have an undesirable degree of moisture sensitivity, see U.S. Pat. No. 3,855,134.
Other one-component intumescent agents stated as having good efficiency, a low level of moisture sensitivity, and good adherence to substrates are reported in U.S. Pat. No. 3,855,134. However, many of these new intumescent agents intumesce with a slight self-extinguishing flame which makes them less desirable for applications having very stringent requirements. Therefore, U.S. Pat. No. 3,855,134 discloses a method for combining said new intumescent agents with halo-organophosphorus compounds to render the normally self-extinguishing intumescent agents non-flaming.
This application is directed to one-compound intumescent agents having good efficiency, excellent hydrolytic stability, good adherence to substrates, and possessing inherent non-flaming intumescent characteristics.